Structural and Magnetic Properties of Mn-Based Diluted Magnetic Semiconductors and Alloys

Direct supercell approach calculations of the magnetic exchange interactions in Mn-doped ScN was carried out in the local spin density approximation by using the muffin-tin-orbital Green's function method. We found that magnetic interactions are long range interactions and affected by the randomness, band gap corrections, and carrier concentrations. Using total energy minimization approach we found that the global energy minimum of MnN is obtained for zinc-blende structure. If the compound is compressed by 6%, the energy minimum corresponds to the rock-salt structure in disagreement with the experimentally observed tetragonal distorted rock-salt structure, known as -phase. An isostructural phase transition for alloys from MnN -phase to -ScN phase was found to occur at a hydrostatic pressure of 18 GPa. We predict above room temperature for Mn concentrations of about 10% in ScN : Mn system.

On “GSI Oscillations” as Interference of Two Closely Spaced Ground Mass Eigenstates of H-Like Mother Ions

We analyse the hypothesis that the “GSI oscillations” of the K-shell electron capture decay (EC) rates of the H-like heavy ions are caused by quantum beats from a coherent state of two closely spaced ground mass-eigenstates and of decaying H-like heavy ions. We apply this mechanism to the calculation of the -decay rates of the H-like heavy ions and discuss the dynamics of the production of the H-like heavy ions with two closely spaced ground mass-eigenstates at GSI experiments. We show that such a mechanism cannot describe simultaneously the experimental data on both the EC-decay and -decay rates of the H-like heavy ions, measured at GSI.

Waveguide Parameters of 19.8 kHz Signal Propagating over a Long Path

The amplitude and phase of 19.8 kHz signal from navigational transmitter located in North West Cape, Australia, recorded at Suva, Fiji, have been utilized to determine the waveguide mode parameters. The propagation path is mixed over land and sea having Transmitter-Receiver Great Circle Path distance 6.7 Mm. The experimental values of the parameters were found to be consistent with the theoretical values calculated using the mode theory of VLF wave propagation in the waveguide.

On the Appearance of a Cooper Minimum in the Photoionization Cross Sections of the Plasma-Embedded Li Atom

The plasma screening effect is found to uncover a Cooper minimum in the photoionization cross sections from the ground state of the Li atom embedded in Debye plasma environment. The variation of the location of this minimum with Debye screening length is discussed and analyzed in terms of the instability of the ground state.

Reality of the Wigner Functions and Quantization

Here we use the extended phase space formulation of quantum statistical mechanics proposed in an earlier work to define an extended lagrangian for Wigner's functions (WFs). The extended action defined by this lagrangian is a function of ordinary phase space variables. The reality condition of WFs is employed to quantize the extended action. The energy quantization is obtained as a direct consequence of the quantized action. The technique is applied to find the energy states of harmonic oscillator, particle in the box, and hydrogen atom as the illustrative examples.

Maximise Global Gain in the Minority Game

We find a simple, partially altruistic mechanism that can increase global gain for a community of selfish agents. The mechanism is implied in the phenomena found in the minority game. We apply the mechanism to a two-road traffic system to maximise traffic flow.

Evaluation of the Thickness in Nanolayers Using the Transfer Matrix Method for Modeling the Spectral Reflectivity

The reflectivity spectra have been traditionally used to determine the thicknesses in semiconductor films. However, thicknesses of nanofilms are not easy to evaluate because the interference fringes are not visible in the transparent region. In this paper, we present a computed method based on the transfer matrix (TM) which is used to match the calculated and experimental room temperature reflectivity spectra of the ZnTe/GaAs films and to determine its thickness film values afterwards. The TM method needs only to know refraction indices and absorption coefficients as a function of wavelength for the film and the substrate. The thickness nanofilms evaluated by our method are in agreement with the values measured by ellipsometry, Rutherford backscattering spectroscopy and transmission electron microscopy techniques. The present procedure extends the application of the standard spectral reflectance technique to determine semiconductor nanolayer thicknesses.

The Spatiotemporal Oscillations of Order Parameter for Isothermal Model of the Surface-Directed Spinodal Decomposition in Bounded Binary Mixtures

The asymptotical behavior of order parameter in confined binary mixture is considered in one-dimensional geometry. The interaction between bulk and surface forces in the mixture is investigated. Its established conditions are when the bulk spinodal decomposition may be ignored and when the main role in the process of formation of the oscillating asymptotic periodic spatiotemporal structures plays the surface-directed spinodal decomposition which is modelled by nonlinear dynamical boundary conditions.

Observation of Suprathermal Flux from SROSS-C2 Data at Low Latitude

The studies of suprathermal flux at equatorial latitude for low solar activity year of 1996 (from January to December) are reported. The retarding potential analyzer (RPA) data of Indian space research organization Stretched Rohini Satellite Series-C2 (SROSS-C2) are used. The suprathermal electron flux data are chosen in the height range of km. Seasional, latitudinal, and height variations of suprathermal flux having energy range above 30 eV along with comparisons in latitudinal variation of small energy superathermal flux of 5 eV are also reported. The data are selected during the period of local midnight to avoid contaminations from photoelectron flux and flux coming from coating of electrodes.

Effect of Sm Substitution on Structural, Dielectric, and Transport Properties of PZT Ceramics

The polycrystalline samples of Pb1−xSmx (Zr0.45Ti0.55)1−x/4O3 (PSZT) (where x = 0.00, 0.03, 0.06, and 0.09) were prepared by a high-temperature solid-state reaction technique. Preliminary X-ray structural analysis of the materials at room temperature has confirmed their formation in single-phase with tetragonal crystal structure. The temperature dependence of dielectric response of the samples at selected frequencies has exhibited their phase transition well above the room temperature. The variation of ac conductivity with temperature and the value of activation energy reveal that their conduction process is of mixed type (i.e., singly ionized in ferroelectric region and doubly ionized in paraelectric phase).